Rotary solenoid



A. A. MOLITOR ROTARY SOLENOID Jan. 5, 1965 3 Sheets-Sheet 1 Filed Sept.4, 1962 Jan. 5, 1965 A. A. MOLITOR 3,164,733

ROTARY SOLENOID Filed Sept. 4, 1962 3 Sheets-Sheet 2 INVEN TOR.

1965 A. A. MOLITOR 3,164,733

ROTARY SOLENOID Filed Sept. 4, 1962 3 Sheets-Sheet 3 INVENTOR.

I z/k/ [KW/er United States Patent 3,164,733 ROTARY SOLENGID Arvid A.Molitor, 1136 Morningside Drive, Elgin, Ill. Filed Sept. 4, 1962, Ser.No. 221,226 4 Claims. (Cl. 310 37) This invention relates to a rotarysolenoid having particular application in the field of stepping motors.

A primary purpose of the invention is a stepping-type rotary solenoid inwhich a single coil provides the turning power for the solenoid and themagnetic force for operating the clutch.

Another purpose is a rotary stepping motor of the type described havinga torsion spring coupling to provide a fast-acting switch.

Another purpose is a rotary solenoid of the type described in which theopposing faces of the armature and pole pieces are conical, andparallel.

Another purpose is to provide a rotary stepping switch of the typedescribed in which the turning torque at the output shaft under serviceconditions approaches as closely as possible a general constant from thebeginning of the stroke to the end of the stroke.

Another purpose is a rotary solenoid which will withstand shocks orvibration in any direction.

Other purposes will appear in the ensuing specification, drawings andclaims.

The invention is illustrated diagrammatically in the following drawingswherein:

FIGURE 1 is a left-end view of the solenoid,

FIGURE 2 is a section along plane 2--2 of FIGURE 1,

FIGURE 3 is a section along plane 33 of FIGURE 2,

FIGURE 4 is a section along plane 44 of FIGURE 2, with parts removed,

FIGURE 5 is an enlarged axial section illustrating the armature, coreand pole pieces,

FIGURE 6 is a left-end view of FIGURE 5,

FIGURE 7 is an axial section similar to FIGURE 2 of a modified form ofsolenoid, and

FIGURE 8 is a view in part section along plane 3-8 of FIGURE 7.

A housing indicated generally at 10 may mount a suitable indicating knob12 at one end along with a position indicating plate 14. The oppositeend of thehousing It) may mount an output shaft 16.

Within the housing It) is an annular coil 18, used to provide the rotaryand clutching magnetic force. Within the coil 18 is a rotatable coremember 20, generally cylindrical in shape, and having a shaft 22extending outwardly from the left-hand end, as illustrated in FIGURE 2.The indicating knob 12 may be attached to the outside end of the shaft22. Concentric with the shaft 22 and adjacent the core 20 is an armature24 illustrated in detail in FIGURES 5 and 6. In radial alignment withthe armature 24 and concentric with it are a pair of pole pieces 26which are part of an annular frame member indicated genorally at 28. Asillustrated in FIGURE 2, the frame member. encloses the coil 18. Themagnetic circuit through the frame member, pole pieces and armature iscompleted by a back frame plate 30, with all of the above listed membersbeing formed of a suitable magnetic material.

Turning to FIGURES 5 and 6, the opposing faces of the pole pieces andarmature are spiral shaped. They are always parallel to each other,regardless of the particular angular position of the armature relativeto the pole pieces, so that the magnetic lines of force between thearmature and the pole pieces will always be normal or perpendicular toboth the armature and the pole pieces. In this way, the magnetic forceof attraction is stronger for the same size air gap and the same crosssectional area of pole piece and armature face. As shown herein thereare two spiral 3,164,733 Patented Jan. 5, 1965 all surfaces, on thearmature, which is symmetrical, and each of the spiral surfaces on thearmature are in opposition to a like spiral surface on a pole piece. Thespiral surfaces on the armature and the pole pieces preferably all havethe same lead.

When the armature rotates through an angle B, as described hereinafter,it will move toward contact with the pole pieces. Preferably thearmature will be stopped before there is actual contact. In any event,the armature will rotate toward the pole pieces and the air gap S willbe shortened or reduced in size as the armature moves.

As illustrated particularly in FIGURE 5, the spiral surfaces 32 of thepole pieces and the spiral surfaces 34 of the armature are conical withthe surfaces being slanted inwardly toward the core.

a radial component of magnetic force. By forming the opposing surfacesof the pole piece and armature in the shape of a cone, the opposingcross sectional areas of the pole pieces and armature are increased.Accordingly, the force component Fm normal to these surfaces, thesurfaces always being parallel, will be larger because of the largercross sectional area. This force component has a radial component Fr,and an axial component Fa. The radial component may be the same inmagnitude as the axial component depending upon the angle of thesurfaces 32 and 34.

The axial component of force is useful to operate the clutch. The core2% has a face 36, which may be slightly out back toward the center, asat 38, which is in opposition to the inner annular surface of thearmature. When the coil is energized, the armature will move in a rotarydirection T due to the radial component of force. At the same time thearmature will move sufficiently so that there is firm contact betweenthe armature and core. Ac cordingly, the core will rotate with thearmature. The inside surface of the armature, 40, may mount a suitablebearing sleeve d2 so that the armature may rotate freely about the shaft22 extending outwardly from the core on its return stroke.

Considering FIGURE 2, the core shaft 22 may be mounted in a bearing 44,with the bearing in turn being held in position in a portion of thehousing 10 indicated at 46. A pair of washer-like springs 48 may be usedto bias the bearing against a shoulder 50 on the shaft 22. Outside ofthe housing portion 46 is a cap 52 Within which is mounted a coil spring54 having a portion 56 which normally biases or urges the armature in adirection oppo-' site that to which it moves by the magnetic force.

Considering FIGURE 4, the armature 24 may have a plurality, for exampletwo, outwardly extending pins or projections 58 which move in slots 60in that portion of the housing immediately adjacent the armature. Thecircumferential extent of the slots 60 determines the angular movementof the armature. A spring stop 62 may be mounted in a slot 64 in the endof the housing and may be positioned to stop the armature just prior tothe end of its movement set by the length of the slots 60. A screw orthe like 66 holds the spring stop 62 in position.

Fixed to the output shaft 16 and to the core 20 may be a detent wheel 68having a series of notches 70. .A detent including a spring '72 mountinga button or the like 74 is suitably fastened to the main housing. Thedetent is effective to hold the detent wheel, core and output shaft in astationary position until there is sufficient turning force from thearmature to overcome the load of a snap action switch and then move thewheel to the next position.

The number and size of notches will depend upon the steps the motor isto take in rotation. The output shaft 16 may be mounted in a suitablebearing or the like 76 which in turn is mounted in an inward sleeveextension 7 3 of the housing In.

In this way it is possible to I develop an axial component of magneticforce as well as Considering FIGURES 7 and 8, those parts correspondingto the parts in FIGURES 1-4 have been given the same numbers. The coremay have an axial bore 8t) with a threaded spring terminal 82 at itsinward end. The spring terminal may be pinned, as at 84, to the core. inalignment with the bore 8%) in the core is an output shaft 86, the outerend of which has a cam 88. The inner end of the outward shaft 86, or theend toward the solenoid, has a threaded spring terminal 91). A suitablecoil spring 91 may be mounted within the bore 8% and positioned on thespring terminals 82 and 96. In operation, as the core turns with thearmature, the spring will be wound up and after it has been tensioned asufiicient amount, it will snap the output shaft and earn from oneposition to the next. The cam may be positioned within a concentricarrangement of switches or some other similar type of load. Movement ofthe armature and core will rotate the cam so that it operates each ofthe desired loads in succession.

In some applications it is advantageous to adjust the return stroke ofthe armature. For example, the speed of the output shaft may beadjusted. The housing it as shown in FIGURES 7 and 8, may have a housingextension 92 along one side. A manual speed control knob 94 may bemounted on a shaft 96, the shaft 96 mounting a cam 98 within the housing92. The cam 98 may bear against a lever 19% which is fixed to arotatable pin 192, also journaled in the housing 92. A second lever 1e4-is fixed to the pin 102 and has an outer somewhat curved end 1% which isadapted to bear against and move the head of the pin 58 extendingoutwardly from the armature. The knob 94 is effective to control thecharacteristics of the stroke of the armature through the structuredescribed above. Since the pulses can be timed equally, the net resultis speed control of the output shaft. The invention should not belimited to this precise arrangement for varying the return stroke, asmany other structural arrangements will be equally satisfactory.

The use, operation and function of the invention are as follows:

Considering a stepping motor as shown in the drawings,

when the coil 18 is activated by a suitable source of electric current,for example pulses or otherwise, there will be a magnetic field formedin the frame members, the armature and the core in such a way that thecore, which is normally freely rotatable, will be held to the armature,which is also freely rotatable, and the armature and core will then berotated in such a manner that the armature moves toward contact with thepole pieces. Normally there will be some means of stopping movement ofthe armature prior to actual contact with the pole pieces. There will berotary motion of the armature and some axial motion as it moves intofirm contact with the core. The armature and core will move the detentwheel a single step as norm-ally the angular movement of the armaturewill correspond with one step on the wheel. Once the current in the coilis turned off, the armature will be rotated back to its originalposition, but the core and output shaft will remain stationary.

Considering FIGURES 7 and 8, the output shaft is attached to the core bythe spring 91. As the armature and core move, the spring 91 will bewound up or tensioned. As soon as the tension in the spring combinedwith the rotary force of the armature is sufficient to overcome theholding force 011 the cam end of the output shaft, the shaft will berotated one step in the forward direction. In some applications a detentwheel may be placed on the end of shaft 36 to replace the cam.

. Although it is not necessary to use the spring 91, it has been foundthat faster switching can be provided with the torsion spring coupling91. If there were no spring, the torque or moving force of the shaft 86at the beginning of its stroke would be somewhat small and would buildup as the armature gets closer to the pole pieces and as the magneticforce of attraction increases. By

using the spring arrangement it is possible to have increased starttorque at the output shaft 36. Also, the turning of the output shaftwill be much greater. t is the combination of the turning force providedby the armature and the force provided by the spring after it has beenWound up by the armature that provides fast action and torque at theoutput shaft.

Of particular importance is the use of conical or slanted faces on theopposing surfaces of the armature and pole pieces. In this way, it ispossible to have an axial component of the magnetic force of attractionwithout detracting from the radial or turning component. The angle thatthe conical faces of the armature and pole pieces make with the axis ofrotation can vary, although angles from 45 to 60 degrees are preferredWith 45 degrees being a very satisfactory angle. The precise angle willbe depend upon the amount of axial force necessary to hold the core tothe armature and upon the amount of turning force necessary at theoutput.

The shape of the face of the core which contacts the armature isimportant. This face may be cut back so that there is only a small areaof actual contact between the armature and the core. This is importantin order to reduce residual magnetism in the core and to provide asmaller area of sliding contact between these two faces. In operation,the coil spring 54 will rotate the armature back to its originalposition after both the armature and core have been turned by themagnetic force. The armature moves in both directions, forward and back,and the core moves only in a forward direction.

Of importance is the spiral shape of the opposing faces of the armatureand pole pieces. The lines of flux or the magnetic field between thepole pieces and the armature will always be perpendicular to theopposing face of these members and will be tangent to a circleconcentric with the axis of rotation. There is therefore a turningforce, or moment arm, about the axis of rotation which provides theturning force for the armature. Preferably, the circumferential extentof the pole pieces is kept at a minimum to concentrate the magneticflux.

The invention should not be limited to a stepping motor, but has equalapplication to a rotary solenoid with only a back and forth movement.

The stepping motor shown herein may be used in counting pulses, and maybe used to actuate a series of devices which are arranged around theoutput shaft. There are many other applications for the invention, bothas a stepping motor and as a rotary solenoid.

The solenoid is not affected by vibrations or shock in any direction.The unit is very compact with all rotating components mounted inbearings.

Whereas the preferred form of the invention has been shown and describedherein, it should be realized that there are many modifications,substitutions and alterations thereto, Within the scope of the followingclaims.

I claim:

1. A rotary solenoid including a rotary core and a pair of pole pieces,concentric with the core, and circumferen tially spaced, one from theother, an armature positioned between and in general radial alignmentwith the pole pieces, said armature having spiral-like outer surfacespositioned opposite said pole pieces, said pole pieces each havingspiral-like surfaces positioned opposite the spirallike surfaces on thearmature, a magnetic coil positioned to form a magnetic field betweenthe pole pieces and armature and to rotate the armature within the polepieces with the spiral-like surfaces of the armature moving, in onedirection, toward the spiral-like surfaces of both pole pieces, a springarranged to move said armature in the opposite direction, an outputshaft, detent means connected to said output shaft, yielding meansholding said detent means and output shaft in a stationary angularposition, and means connecting said output shaft to said armature whenthe coil is energized including a spring member effective between saidshaft and core, rotary 5 i movement of said armature and core caused byenergizing said coil applying a turning force to said spring member,which turning force overcomes the yielding means holding said detentmeans after a given rotation of said armature and core.

2. The structure of claim 1 further characterized in that said springmember extends within said core andis fixed to said output shaft.

3. The structure of claim 1 further characterized in that said springmember is fixed to said core.

4. The structure of claim 1 further characterized in that the opposingspiral-like surfaces of the armature and pole pieces are conical.

6 References Cited by the Examiner UNITED STATES PATENTS 928,516 7/09Heilmund 31036 X 2,460,921 2/49 Candy 317-197 X 2,963,915 12/60 Straub317-197 2,937,657 6/61 Buchtenkirch et a1. 317-192 FOREIGN PATENTS753,262 8/33 France.

MELTON 0. HIRSHFIELD, Primary Examiner.

JOHN P. WILDMAN. Examiner.

1. A ROTARY SOLENOID INCLUDING A ROTARY CORE AND A PAIR OF POLE PIECES,CONCENTRIC WITH THE CORE, AND CIRCUMFERENTIALLY SPACED, ONE FROM THEOTHER, AN ARMATURE POSITIONED BETWEEN AND IN GENERAL RADIAL ALIGNMENTWITH THE POLE PIECES, SAID ARMATURE HAVING SPIRAL-LIKE OUTER SURFACESPOSITIONED OPPOSITE SAID POLE PIECES, SAID POLE PIECES EACH HAVINGSPIRAL-LIKE SURFACES POSITIONED OPPOSITE THE SPIRALLIKE SURFACES ON THEARMATURE, A MAGNETIC COIL POSITIONED TO FORM A MAGNETIC FIELD BETWEENTHE POLE PIECES AND ARMATURE AND TO ROTATE THE ARMATURE WITHIN THE POLEPIECES WITH THE SPIRAL-LIKE SURFACES OF THE ARMATURE MOVING, IN ONEDIRECTION, TOWARD THE SPIRAL-LIKE SURFACES OF BOTH POLE PIECES, A SPRINGARRANGED TO MOVE SAID ARMATURE IN THE OPPOSITE DIRECTION, AN OUTPUTSHAFT, DETENT MEANS CONNECTED TO SAID OUTPUT SHAFT, YIELDING MEANSHOLDING SAID DETENT MEANS AND OUTPUT SHAFT IN A STATIONARY ANGULARPOSITION, AND MEANS CONNECTING SAID OUTPUT SHAFT TO SAID ARMATURE WHENTHE COIL IS ENERGIZED INCLUDING A SPRING MEMBER EFFECTIVE BETWEEN SAIDSHAFT AND CORE, ROTARY MOVEMENT OF SAID ARMATURE AND CORE CAUSED BYENERGIZING SAID COIL APPLYING A TURNING FORCE TO SAID SPRING MEMBER,WHICH TURNING FORCE OVERCOMES THE YIELDING MEANS HOLDING SAID DETENTMEANS AFTER A GIVEN ROTATION OF SAID ARMATURE AND CORE.